Didier Jambart, 52, of Nantes, France, sued the pharmaceutical giant GlaxoSmithKline in 2011, claiming the drug, Requip, caused him to lose 82,000 euros gambling on the Internet. He said he also became addicted to gay sex and risky sexual encounters. He said he was raped after starting the drug in 2003 and attempted suicide eight times.

"It's a great day," Jambart, who was accompanied by his wife during the emotional ruling, told the French Press Agency. "It's been a seven-year battle with our limited means for recognition of the fact that GSK lied to us and shattered our lives."

Parkinson's disease destroys neurons deep within the brain that release the "feel-good" neurotransmitter dopamine. Requip belongs to a class of drugs called dopamine agonists that relieve Parkinson's symptoms -- such as shaking, stiffness, slowness and trouble balancing -- by activating dopamine receptors. But the drugs have side effects that, while rare, can be serious.

"There are plenty of reports of people developing side effects from Parkinson's drugs, such as hypersexuality, gambling and excessive shopping," Dr. David Standaert of the Center for Neurodegeneration and Experimental Therapeutics at the University of Alabama at Birmingham told ABC News when the lawsuit was filed. "It's uncommon, but very dramatic when it happens."

Up to 17 percent of people with Parkinson's disease who take dopamine agonists exhibit an impulse control disorder, according to a 2010 study published in the Archives of Neurology.

"It can be devastating for those people," said Dr. Mark Stacy, the Duke University neurologist who first linked the drugs to gambling in 2000. "And I think that because of the embarrassing nature of the complaint, it's a bit amplified."

Jambart is not the first Parkinson's patient to sue a drug maker over these symptoms. In 2008, a court in Minneapolis awarded Gary Charbonneau $8.2 million in a suit against the makers of Mirapex, Pfizer and Boehringer Ingelheim. And in 2010, more than 100 patients in Australia sued Pfizer and Aspen Pharmacare -- the makers of Cabaser and Permax respectively -- over sex and gambling addictions.

"Dopamine is a reward signal," Standaert said, adding that certain illicit drugs, such as cocaine and methamphetamine, act on dopamine receptors. Standaert said he has met patients who have gambled or shopped away hundreds of thousands of dollars. "In certain individuals who seem sensitive to this, these dopamine agonists really make them overcome their normal inhibitions… They lose their moral compass."

Compulsive behaviors such as pathological gambling and hypersexuality are now listed as side effects on the drugs' package inserts. But Jambart claimed this wasn't the case when he starting taking Requip in 2003. By the time he stopped taking Requip in 2005, he had already been demoted at work and suffered psychological trauma because of his addictions, his lawyers told the French Press Agency.

In the United States, GSK added warnings about unusual behaviors to the Requip package insert in July 2005 and expanded them in 2006, company spokeswoman Mary Anne Rhyne told ABC News at the time the lawsuit was filed.

"We urge patients to talk to their doctor before deciding to stop or start taking any medicine," she said. "Anyone receiving treatment with dopamine agonists who notices unusual behaviors, such as new or increased gambling urges, increased sexual urges or other intense urges should talk to their doctor."

Standaert stressed that while the drug's side effects are "colorful and serious," they're very rare.

"These are very useful medications," he said. "People shouldn't be frightened, they should just know about the risks."